This application relates to an internally cooled turbine blade for use in a gas turbine engine, wherein an impingement rib which meters flow of air into a pedestal array has a split lower portion.
Gas turbine engines are known, and include a plurality of sections, typically serially connected. A fan section supplies air to a compressor section. The compressor section compresses the air and delivers it to a combustion section. The combustion section combusts the air with a mixed fuel, and passes the products of combustion downstream over turbine rotors. The turbine rotors are driven to rotate, and in turn create power, and rotate the fan and compressor sections.
Typically, the turbine section includes a plurality of rotors each mounting a plurality of blades. The blades are exposed to relatively high temperature from the products of combustion. Thus, it is known to provide cooling air internally within the blades.
Each turbine blade typically includes a root section for being mounted within the rotor, a platform section, and then an airfoil extending outwardly from the platform section. The airfoil is generally hollow and includes cooling channels. Design of the cooling channels takes into account a number of different stresses and challenges on the blade. One type of structure used in the cooling channels is found adjacent what is known as the trailing edge of the airfoil. It is known in the prior art to provide an array of pedestals extending between two spaced walls adjacent the trailing edge. The pedestals serve to disrupt the air flow and also serve as heat sinks to allow the air to remove heat from the airfoil. It is known to provide an impingement rib, or generally a separating wall, separating an open air channel from the pedestals. A plurality of cross-over holes extend through the impingement rib to meter the flow of air into the pedestal array.
One challenge with the prior art turbine blades is that there are high stresses on the impingement rib, in particular at an area adjacent to the platform. This high stress concentration can result from a plurality of loads that are found at the connection of the airfoil to the platform.